Discharge lamp and stem therefor



0 uw., J .L M RK WY w 3. Tg2/ 4 z y wm a, I v Til, 4 2 O z i 1|! v/ T. T v1, All W c C WIENER DISCHARGE LAMP AND STMS THEREFOR Original Filed Dec. 30, 1938 May 1l, 1943.

Patented May 1l, 1943 DISCHARGE LAM? AND STEM THEREFOR Charles Wiener, Bloomfield,

N. J., assignor to Westinghouse Electric & Manufacturing Company, East PittsburghPa., a corporation of Pennsylvania Original application Dece 248,4l8. Divided an 1942, Serial No. 449,059

5 Claims.

This application is a division of my co-pending application, Serial No. 248,418, filed December 30, 1938,` for Making lamp stems, and owned by the assignee of the present application.

The invention relates to discharge lamps and stems therefor, and especially to such stems of glass or other suitable vitreous material for lamps of the fluorescent type.

The principal object of my invention, generally considered, is the provision of an improved fluorescent lamp, and especially a stem therefor having novel desirable characteristics.

Another object of my invention is a stem, particularly adapted for discharge lamps, in which the walls thereof are as nearly uniformly thin as is possible, and in which the exhaust tube thereof passes therethrough so that it opens axially of the associated envelope.

A further object of my invention is the provsion of lamp stems that are uniformly thin and which will not crack when heat is applied thereto, as during the sealing operation.

Other objects and advantages of the invention, relating tothe particular arrangement and construction of the various parts, will become apparent as the description proceeds.

Referring to the drawing:

Fig. 1 is an axialv sectional view of one end portion of a fluorescent lamp embodying my inveition'.

Fig. 2 is a transverse sectional view on the line II-'II of Fig. 1, in the direction of the arrows.

Fig. 3 is an axial sectional view of a spindle andv associated apparatus for making a stem for a lamp such as illustrated in Figs. 1r and 2.

Fig. 4 is a transverse sectional view on the line IV-IV 0f Fig. 3, in the direction of the arrows.

Figs. 5, 6, and 7 are views similar to Fig. 3 but illustrating subsequent successive stages in the formation of a stem embodying my invention.

In manufacturing discharge lamps, and more particularly such of the fluorescent type, it is desirable to have the stems thereof formed of uniformly thin glass, with the exhaust tube axially disposed, so as to avoid stem cracks, and be able 1- to fill said lamps without danger of the filling material destructively impinging against the fluorescent coating. It is desirable that a thick glass press be avoided, not only from a standpoint of appearance, but also because of the danger of cracking. My invention accomplishes the foregoing objects in providing, by methods suitable for mass production, a glass stem particularly adapted for, but not limited to, use with fluorescent lamps, and which is both uniformly mber 30, 1938, Serial No. d this application June 30,

thin and strong enough for the purpose intended.

In Figs. 1 and 2 there is illustrated one end portion of a fluorescent lamp having a tubular envelope I0 with an interior coating II of fluorescent material. This envelope has sealed thereto a stem I2 carrying a filament I3, supported therefrom by leads I4 and I5 sealed through the upper or inner reentrant arched annular 0r toroidal portion I6 which connects the flare 26 or generally cylindrical collar portion 21, thereof, with the exhaust tube or tubulation I'I. 'I'he frusto-conical or outer flaring portion 36 is sealed to the envelope II. It will be seen that said eX- haust tube I'I is disposed axially of the stem I2 and envelope ID, whereby during the process of filing the lamp the usual gas and mercury is discharged axially, rather than radially, thereby avoiding danger of damaging the fluorescent coating II.

Figs. 3 and 4 illustrate apparatus adapted to produce stems embodying my invention, and holding the elements of a stem prior to being united. The spindle 20 of the device has two openings or pockets 2I and 22 formed on opposite i sides of a central, larger opening or pocket 23.

These openings 2| and 22 are of such diameter that they provide pockets to respectively hold lead-in conductors I4 and I5 and the central pocket 23 normally receives a tubulation or exhaust tube I'I. This tube I1 is desirably preformed with conical or flaring upper portion I8 to facilitate the formation of my improved stem.

The pockets 2I, 22 and 23 are of such depths that the rim or outer periphery of the flaring portion I8 of the exhaust tube I'I is disposed at the level of, and almost touches, the intermediate portion 24 of the conductors I4 and I5, which portion is preferably of the familiar copper-clad nickel-iron alloy, usually referred to as Dumet. The upper portions of the conductors may be of nickel, as may also be the portions below the Dumet 24, although said lower portions may be of other suitable conductive material such as copper.

The spindle 20 has a conical upper surface 25 adapted to nest with and support the frusto-conical portion 36 of a flare tube 26, having a tubular or generally cylindrical collar 21, of such a diameter that it closely surrounds the wires I4 and I5 when held in the pockets 2| and 22. 'I'he tubular collar 21 terminates at its rim 28 a short distance above or beyond the flaring portion or flange I8 of the exhaust tube I1. When the flare tube 26 has been positioned, a perforated centering thimble 30 is disposed thereover, closely tting it and the spindle 2li, or a sleeve 3I secured thereto.

The spindle 2B has one or more, preferably two, openings, 32 and 33 which, as disclosed in Figs. 4 and 5, are not mere pockets but passages which extend from the upper conical surface 25 of the spindle, on opposite sides of the pocket 23, to a conduit 34 containing a gaseous medium such as air under regulated pressure. rIhese two openings may be located symmetrically with respect to the pockets ZI and 22 for the conductors I4 and I5, as shown most clearly in Fig. 4.

One way of making a stem embodying my invention, is to revolve the spindle 20 and heat the upper edge 28 ofthe tubular collar portion 2l of the are tube I2, as by means of gas flames 35, as shown in Fig. 5. The heat from said flames melts the upper edge portion 28 of the said glass collar 21 and causes it to contract around the Dumet portions 24 of the conductors i4 and I5, as well as against the adjacent edge of the flared portion I8 of the exhaust tube I1, as shown most clearly in Fig. 6. This application of heat forms a seal between the exhaust tube Il and the are tube 26. Ordinarily, this seal would be a sharp inverted V in section, with thick sides. Such a seal would be weak and apt to crack in the crotch of the V. Annealing of the glass forming such a seal would be very slow because of the thickness of the glass and undesirable strains would result therein.

In accordance with my invention, I make my improved stem by applying air or other gas, such as the inert gas nitrogen, under pressure through the openings 32 and 33. to round out the annular hollow portion I6 while still soft, as illustrated in Fig. '7, into a regular arched or toroidal portion, in order to avoid strains in the seal. This gaseous pressure also provides the toroidal portion with a thin wall, where the conductors I4 and I5 pass therethrough, uniform in thickness with the remainder of the stem. Due to this uniformity of the walls of the stem, embodying my invention, the same may be rapidly annealed to remove undesirable strains.

A consideration of the foregoing will show that I have provided an improved form of discharge lamp and stem therefor, in which the glass is of substantially uniform thickness throughout,

thereby adapting it for uniform and quick an- 7 nealing. The exhaust tube is not only disposed axial of the stem and discharge tube envelope, but opens axially of the latter, thereby avoiding damage to the fluorescent material on the inner surface during the process of filling the lamp.

Although a preferred embodiment of my invention has been disclosed, it will be understood that modications may be made within the spirit and scope of the appended claims.

I claim:

1. A stem for a lamp comprising a frusto-conical glass element from the inner peripheral portion of which extends a substantially cylindrical portion, a glass exhaust tube portion disposed within said substantially cylindrical portion, an arched annular glass portion uniting the corresponding end portions of said substantially cylindrical and exhaust tube portions, and lead conductor means disposed in the annular space between said substantially cylindrical and glass tube portions and passing through said annular glass portion, the thickness of said glass being substantially uniform throughout said stem.

2. A vitreous stem for a lamp comprising a flare portion, an exhaust tube portion disposed axially thereof and a vitreous arched annular portion uniting the corresponding end portions of said flare and exhaust tube portions, the thickness of the vitreous material being substantially uniform throughout said stem.

3. A glass stem for a lamp comprising a flare portion, an exhaust tube portion disposed axially thereof, an arched annular glass portion uniting the corresponding end portions of said flare and exhaust tube portions-and lead in conductors disposed in the annular space between said flare and exhaust tube portions and intersecting said annular glass portion, said stem having its Walls of substantially uniform thickness throughout.

4. A glass discharge lamp comprising an elongated envelope, a stem comprising a frusto-conical portion sealed at its outer periphery to one end of said envelope, a substantially cylindrical portion extending from the inner peripheral portion of said frusta-conical portion, an exhaust tube disposed within said substantially cylindrical portion, an arched annular glass portion uniting the corresponding end portions of said substantially cylindrical and exhaust tube portions, and lead-in conductor means disposed in the annular space between said substantially cylindrical and exhaust tube portions and intersecting said annular glass portion, the thickness of said glass being substantially uniform throughout.

5. A glass discharge lamp comprising a cylindrical envelope, a stem comprising a frusto-conical portion sealed at its outer periphery to one end of said envelope, a substantially cylindrical portion extending from the inner peripheral portion of said frusto-conical portion, an exhaust tube disposed within said substantially cylindrical portion, and an arched annular glass portion uniting the corresponding end portions of said substantially cylindrical and exhaust tube portions, the thickness of said glass being substantially uniform throughout.

CHARLES WIENER. 

